The inventive subject matter relates to circuit breakers and methods of fabricating the same and, more particularly, to circuit breakers with magnetic armature trip mechanisms and methods of fabricating the same.
A circuit breaker may include a trip mechanism with a magnetically-actuated armature that is used to actuate a breaker mechanism that separates contacts in the breaker to interrupt a circuit. In some breakers, the armature includes an armature plate or similar structure that is displaced by a magnetic force generated by a current flowing through a conductor (e.g., a bus bar) magnetically linked to the armature plate. Movement of the armature plate causes a trip bar coupled thereto to rotate, causing the breaker mechanism to open the breaker contacts.
In some breakers, the armature plate is coupled to the trip bar using a threaded rod running between the armature plate and the trip bar. It is desirable that this linkage be the proper length so that the breaker trips at a specified current level. Conventionally, this linkage is adjusted using hex nuts, stop nuts and/or other fasteners, which may complicate assembly of the breaker. For example, FIG. 7 illustrates a armature plate 10 that is linked to a trip bar 20 using a threaded rod 30 with a retaining nut 40. FIG. 8 illustrates a similar armature link, except an e-clip 50 is used to retain the end of the link rod 30.